Energy Harvesting and Storage with Lithium-Ion Thermogalvanic Cells

Abstract

Thermogalvanic cells (electrochemical cells under a temperature gradient) are presented as multifunctional power sources, having capabilities for both energy harvesting and energy storage. A symmetric thermogalvanic cell with lithium-ion electrodes has the ability to be charged under a temperature gradient and then discharged when the temperature gradient is removed. Presented here is the first demonstration of a cycled thermogalvanic energy storage cell. Experimental results for dE/dT (the cell voltage produced per degree temperature difference) are given for symmetric thermogalvanic cells with single-phase LixTiS2 or amorphous LixV2O5 electrodes and alkyl carbonate electrolyte solutions. All cells exhibit dE/dT on the order of 1 mV/K. The thermoelectric Seebeck coefficient of the electrode materials and extent of lithium intercalation (x) have slight or negligible effects on thermogalvanic dE/dT. There are slight dependences of dE/dT on the electrolyte anion (PF6− vs BF4−) and electrolyte concentration, and there is no dependence on the electrolyte solvent (EC:DMC vs PC).